JP2914772B2 - Sensor for secondary circuit of ignition circuit of internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor mounted on a secondary circuit of an ignition circuit for applying a high voltage for spark discharge to a spark plug mounted on an internal combustion engine.

[0002]

2. Description of the Related Art An ion current detection circuit including a power supply of several hundred volts is attached to a secondary circuit of an ignition circuit of an internal combustion engine via a high voltage diode, and an ionic current is generated via the high voltage diode. Misfire detection, pre-ignition discrimination, knocking detection, etc. are performed.

[0003]

However, the conventional ionic current detection circuit cannot detect the ionic current while a high voltage is generated in the secondary circuit from spark discharge to ignition, and cannot detect the ionic current during ignition. When the resistance value of the spark discharge gap of the spark plug is high in the state of the airflow in the combustion chamber, the ion current does not flow due to the forward drop voltage of the high-voltage diode, so that the misfire cannot be detected accurately. An object of the present invention is to provide a sensor for a secondary circuit of an ignition circuit of an internal combustion engine, which can detect both an ion current and an induced current and can accurately detect information in a cylinder such as a misfire.

[0004]

SUMMARY OF THE INVENTION A secondary circuit sensor for an ignition circuit of an internal combustion engine according to the present invention is a sensor for a secondary circuit of an ignition circuit connected to a current and voltage detection circuit including a power supply. A lead wire connected to a secondary circuit of the circuit, a high-voltage diode attached to the lead wire, and an induced electromotive force generator having a conductor attached near the secondary circuit are connected in series or in parallel.

[0005]

According to the present invention, the ion current is supplied to the secondary circuit of the ignition circuit to measure the ion current waveform, and the voltage waveform generated in the secondary circuit is detected by the induced voltage. It is possible to accurately detect a combustion state such as a misfire of the vehicle.

[0006]

FIG. 1 shows an ignition circuit 100 for an internal combustion engine, in which a primary coil 1 connected to a battery B and an interrupter D is shown.
1, an ignition coil 1 having a secondary coil 12, and a distributor connected to the secondary coil 12 (distributor)
And a spark plug 3 attached to each cylinder and applied with a high voltage generated by the secondary coil 12 via the power distributor 2.

[0007] A secondary circuit sensor 4 is connected to a secondary circuit 10 between the power distributor 2 and the spark plug 3.
The sensor 4 has one end connected to the secondary circuit 10 and the other end mounted with a current and voltage detection circuit 5 including a power supply of several hundred volts, and a secondary voltage attached to the lead 41. A high-voltage diode 6 for interruption and a part (conductor) between the high-voltage diode 6 of the lead wire 41 and the detection circuit 5 are arranged close to the high-voltage wire of the secondary circuit, and And an induced voltage generating section 7 for generating an induced voltage by an induced electromotive force corresponding to the voltage.

[0008] A negative voltage of several hundred volts is always applied to the secondary circuit 10 by the detection circuit 5. Usually, it is insulated by the air gap of the spark plug 3 and the rotor gap of the distributor 2, and no current flows. Also, while the secondary voltage is being generated, no current flows because the voltage level of the secondary circuit 10 is high. While spark discharge occurs in the spark plug 3 and the air-fuel mixture ignites and burns in the cylinder, the conductivity of the spark discharge gap is increased by ionization of the fuel in the flame, so that the spark discharge gap is increased. The ionic current flows through.

Further, the secondary voltage generated in the secondary circuit 10 causes the induced voltage generating section 7 of the lead wire to have a voltage as shown in FIG.
When ignition or combustion occurs due to spark discharge, an induced voltage waveform b occurs. When a spark discharge occurs, an induced voltage waveform such as c occurs when a misfire occurs. Occur. The ion current and the induced voltage are detected by the detection circuit 5, and a discrimination circuit (microcomputer) (not shown) discriminates misfire, pre-ignition, knocking, and the like.

Since the sensor 4 can detect both the ion current and the induced voltage waveform, the misfire can be accurately detected, and preignition, knocking, etc. can be detected by one sensor. In the above-described embodiment, the induced voltage generating section 7 is configured by a part of the lead wire. However, a conductor having another shape such as a cylindrical body, a coil, and a plate-shaped body may be used.

FIG. 3 shows another embodiment. The ignition circuit 100 is of a direct ignition type in which the voltage of the ignition coil 1 is directly guided to the spark plug 3 without passing through a power distributor. In this embodiment, the high voltage diode 6 is interposed in the secondary circuit 10 to prevent the voltage of the detection circuit 5 from being applied to the ignition coil 1. FIG. 4 shows still another embodiment. In this embodiment, a branch line 42 is provided from a lead wire 41 to serve as an induced voltage generator 7.
And the induced voltage generator 7 are connected in parallel. In these embodiments, the same operation and effect as those of the first embodiment can be obtained.

[Brief description of the drawings]

FIG. 1 is an ignition circuit diagram of an internal combustion engine equipped with a sensor for a secondary circuit of the present invention.

FIG. 2 is a waveform diagram for explaining operation.

FIG. 3 is an ignition circuit diagram of an internal combustion engine equipped with a sensor according to another embodiment of the present invention.

FIG. 4 is a circuit diagram of a sensor according to still another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ignition coil 2 Distributor 3 Spark plug 4 Sensor for secondary circuit 5 Current and voltage detection circuit 6 High voltage diode 7 Induction voltage generator 41 Lead wire

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F02P 17/12

Claims (1)

(57) [Claims] 1. A sensor for a secondary circuit of an ignition circuit connected to a current and voltage detection circuit including a power supply, comprising: a lead wire connected to the secondary circuit of the ignition circuit; and a high voltage diode attached to the lead wire. A sensor for a secondary circuit of an ignition circuit for an internal combustion engine, wherein an induction electromotive force generator having a conductor attached near the secondary circuit is connected in series or in parallel.